The invention involves a system for controlling multiple electronic devices, such as consumer electronic devices or the like, via interconnections such as digital data buses. More particularly, this invention concerns an arrangement for managing the interoperability of such devices.
A data bus can be utilized for interconnecting electronic devices such as television receivers, display devices, video-cassette recorders (VCR), direct broadcast satellite (DBS) receivers, and home control devices (e.g., a security system or a temperature control device). Communication using a data bus occurs in accordance with a bus protocol. Examples of bus protocols include the Consumer Electronics Bus (CEBus) and the IEEE 1394 High Performance Serial Bus.
A bus protocol typically provides for communicating both control information and data. For example, CEBus control information is communicated on a xe2x80x9ccontrol channelxe2x80x9d having a protocol defined in Electronics Industries Association (EIA) specification IS-60. On an IEEE 1394 serial bus, control information is generally passed using the asynchronous services of the serial bus. Control information for a particular application can be defined using for example, Common Application Language (CAL) or AV/C.
Today, most A/V devices are controlled with a remote control (RC) unit. The actual direct or physical link may be implemented with infrared (IR), ultrasound (US) or radio-frequency transmission (RF). The protocol between the peripheral device and the RC unit is device specific such that each device comes with its own RC unit. Each such peripheral device interprets the key presses it receives via its direct link and carries out the corresponding actions. Thus in the case of IR, control of a peripheral or target device is limited to a direct line-of-sight between the RC unit and the peripheral device.
In today""s analog audio/video (A/V) cluster, controlling peripheral devices may include, but do not require, the activation of an On-Screed Display (OSD) mechanism on a display device (i.e., TV). The OSD of such AN devices is generated in the peripheral or target device (e.g., digital VCR) and is output on the NTSC output of such devices the same way as any other video signal. Thus, no additional hardware or software is needed in either the peripheral or the display device. FIG. 1 illustrates a present A/V system 10 having a VCR 12 and a display device 14 (e.g., television) that employs such a control methodology. Menus associated with controlling VCR 12 are generated by the VCR 12 and are provided to the display device 14 via the NTSC output of the VCR 12 as a composite video. Unfortunately, to use the same approach (See FIG. 2) with a digital TV (DTV) as a display device 14xe2x80x2 is not practical since it would require the menus to be transported as MPEG-2 transport streams. Generation of such streams necessitates integrating an MPEG encoder 15xe2x80x2 into all peripheral devices which greatly increases the cost and complexity of such consumer electronic devices.
The present invention provides for a minimal level of interoperability for exchanging audio/video (A/V) content and associated control between common consumer electronic (CE) devices. The interface is based on IEEE 1394 serial bus for the physical and link layers and makes use of a control language such as AV/C or CAL for managing OSDs and controlling the connectivity of devices interconnected via a digital serial bus. Particularly, this invention provides for reducing the number of remote controls that the user might need by allowing remote control commands to always be received by a controlling device (e.g., digital television or DTV) and then routed to the appropriate peripheral device after translation into a universal format. A universal remote message is carried across the serial bus and permits complex applications such as allowing the user to select a program to be recorded using the EPG of the DTV.
Although it will be possible to control each CE device through its own front panel or its own remote control, it is recognized that it is highly desirable to control all devices on the cluster with one remote control. One way to achieve this goal in a wav that furthers interoperability is to use a standard control language (e.g., CAL or AV/C) to carry universal remote control messages across the bus. This would also allow the control of devices which are not directly in the line-of-sight (e.g., devices in a different room or hidden, for example behind a cabinet door) as long as they are on the IEEE 1394 serial bus. Once the user has the peripheral device""s menu displayed on a display device, the display device can relay user initiated commands (i.e., remote control (RC) keystrokes) intended for the peripheral device, received via any appropriate link (for example, IR link). The remote control kevs would be mapped to a common command language, which all consumer electronic devices from any manufacturer would be compliant with, before they are transferred.